Bioaccumulation in Functionally Different Species: Ongoing Input of PCBs with Sediment Deposition to Activated Carbon Remediated Bed Sediments

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When terminating sediment bioaccumulation tests with the oligochaete Lumbriculus variegatus, varying amounts of detrital material are retained along with the recovered worms after sieving, necessitating time-consuming, labor-intensive manual separation of worms from detritus prior to tissue residue analysis. A method to facilitate the worms self-extracting out of the detrital material into a column of gravel was developed, resulting in approximately 90% recovery test organisms (on a mass basis) at test termination. Following exposure to contaminated sediment, polychlorinated biphenyl tissue residues and residual sediment in the gut of self-extracted animals were not significantly different compared to worms recovered by manual separation followed by purging of gut contents.

Section: Self-extraction Versus Manual Separation Methods: Bioaccumulation and Gut Content Comparisonmentioning

confidence: 99%

“…The remaining tissue was weighed and frozen. Tissue samples were extracted with hexane by modified sonication and analyzed for 133 PCB congeners by dual-column gas chromatography combined with electron capture detection, as described in Gidley et al (2019).…”

Section: Self-extraction Versus Manual Separation Methods: Bioaccumulation and Gut Content Comparisonmentioning

confidence: 99%

Streamlining Freshwater Bioaccumulation Bioassays: Letting the Worms Do the Hard Work

Lotufo

Melby

Biedenbach

et al. 2021

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“…Not surprisingly, therefore, it is commonly believed that the source of PCBs to fish is contaminated sediments and has often led to the use of biota sediment accumulation factors (BSAFs) to determine sediment cleanup goals for achieving target Arnot and Gobas (2004) and the simplified thermodynamic model. Both models are parameterized to New Bedford Harbor sediments (Burkhard 2013;Gidley et al 2019). PCB = polychlorinated biphenyl.…”

Section: Relating Concentrations In Fish and Sedimentsmentioning

confidence: 99%

“…FIGURE 5: Relative contribution of the surface water to the uptake of PCBs in several species of New Bedford Harbor as calculated using the food web model(Arnot and Gobas 2004) parameterized to New Bedford Harbor sediments(Burkhard 2013;Gidley et al 2019). Porewater concentrations are calculated based on a K OW correlation.…”

mentioning

confidence: 99%

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Deconvoluting Thermodynamics from Biology in the Aquatic Food Web Model

Ghosh

Bokare

Gobas

2021

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Bioaccumulation of hydrophobic pollutants in an aquatic food web is governed by exposure concentrations in sediment and water phases and by complex trophic interactions among the various species. We demonstrate that biological interactions and exposure from the chemical environment can be deconvoluted for aquatic food webs to allow clearer assessments of the role of thermodynamic drivers from the sediment and surface water phases. We first demonstrate the feasibility of this deconvolution mathematically for hypothetical food webs with 3 and 4 interacting species and for more realistic real-world food webs with >10 species of aquatic organisms (i.e., the freshwater lake food web in Western Lake Erie [ON, Canada] and the marine food web in New Bedford Harbor [MA, USA]). Our results show both mathematically (for the simple food webs) and computationally (for the more complex food webs) that a deconvoluted food web model parameterized for site-specific conditions can predict the bioaccumulation of polychlorinated biphenyls in aquatic organisms same as existing complex food web models. The merit of this approach is that once the thermodynamic and biological contributions to food web bioaccumulation are computed for an ecosystem, the deconvoluted model provides a relatively simple approach for calculating concentrations of chemicals in organisms for a range of possible surface water and sedimentary concentrations. This approach is especially useful for calculating bioaccumulation of pollutants from freely dissolved concentrations measured using passive sampling devices or predicted by fate and transport models. The deconvoluted approach makes it possible to develop regulatory guidelines for a set of surface water and sediment (or porewater) concentration combinations for a water body that is able to achieve a risk-based target for fish concentration.

Interlaboratory Comparison of Three Sediment Bioaccumulation Tests

Lotufo

Biedenbach

Farrar

et al. 2022

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Standard bioaccumulation tests are commonly conducted using Macoma nasuta (clam), and Alitta virens (polychaete) for marine tests, and Lumbriculus variegatus (an oligochaete) for freshwater tests. Because the interlaboratory variability associated with these tests is unknown, four experienced laboratories conducted standard 28-day bioaccumulation tests with the above species using sediments contaminated with polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). Chemical analysis of tissue samples was performed by a single laboratory. The intralaboratory variance among replicates was relatively low for PCB tissue concentrations, with coefficients of variation (CVs) ranging from 9% to 28% for all laboratories and species, with the exception of one laboratory reporting higher variability for L. variegatus (CV = 51%). Intralaboratory variance for PCB tissue concentrations was higher than interlaboratory variance for A. virens and L. variegatus, and the magnitude of difference (MOD) for laboratory means ranged from 1.4 to 2.0 across species. Intralaboratory variability was also low for lipid content, and lipid normalization of PCB and PAH body residues generally had little impact on variability. In addition to variability across bioassay laboratories, analytical variability was evaluated by different laboratories measuring the concentration of PCBs and total lipids in a subsample of tissue homogenate of sediment-exposed test organisms. Variability associated with tissue analysis was higher than bioassay laboratory variability only in tests with L. variegatus. Statistical differences between samples may be observed due to the low intralaboratory variability; however, the biological significance of these differences may be limited because the MOD is low. Considering the MOD when comparing bioaccumulation across treatments accounts for uncertainty related to inherent variability of the test in the interpretation of statistically significant results.